The Odeon Tower’s Sky Penthouse in Monaco may be the world’s most expensive apartment unit upon completion.

The 35,500-square-foot, five-story penthouse will be set atop the second tallest building along the Mediterranean coastline within the Golden Citadel area of Monte Carlo.

The five-bedroom, three-bathroom penthouse features floor-to-ceiling windows offering 360-degree views, a terrace that is connected to a pool by a slide, and utilizes technology and stylish architecture to create a breathtaking skyscraper.

The unit will hit the market with a near-$400 million price tag.